Recently, a GaN-based compound semiconductor has become a focus of attention as a semiconductor material for the short-wavelength light emitting element. The GaN-based compound semiconductor is formed by a metal organic chemical vapor deposition method (MOCVD method), a molecular beam epitaxy method (MBE method) or the like on a substrate composed of a sapphire single crystal, other various oxides or group III-V compounds.
In such a semiconductor light emitting element using the GaN-based compound semiconductor, generally, a laminated semiconductor layer having an LED structure constituted by an n-type semiconductor layer, a light emitting layer and a p-type semiconductor layer is formed on a substrate, and while a transparent electrode and an electrode pad for an external connection (p pad electrode) are formed on the p-type semiconductor layer as the top portion, another electrode pad for an external connection (n pad electrode) is formed on the n-type semiconductor layer that has been exposed by removing part of the p-type semiconductor layer and the light emitting layer by etching or the like.
As a related art disclosed in an official gazette, disclosed is a p pad electrode on the transparent electrode and an n pad electrode on the n-type nitride semiconductor layer, each of which is formed by a laminated structure composed of Au and Cr, and thereby the p pad electrode and n pad electrode have a common structure (refer to Patent Literature 1).